1974 Mt125

[Cutlass372]

Hey guys, i have a 1974 MT125 that needs some help. i am doing a top end right now and hoping that will make it stronger. when i drove it before it was okish in first and second gear but when u get to 3 or 4th it poops out big time; it kinda just maintains speed in 3-4 and doesnt rev out. what would that be? it also doesnt idle but i think thats just dirty carb and stuff? what are some common problems with these bikes? and what do you think my problem is?
Thanks

 

[Colorado]

I don't know the MT that well, but would do the carb first. Completely disassemble it, soak it overnight, then blow it out with air. I then spray it with carb/choke cleaner again, and blow it out again. I particularly do that with the jets, and sometimes, with an old, dirty carb run the point of a wooden toothpick soaked in carb spray through all of the jet holes. Someone will say I shouldn't, but it works for me. DON'T use any hard wire or metal pokers! The pilot jet will affect your idle, and the needle and main your midrange. Replace any questionable O-rings (I've used 'close enough' ones from an auto parts store), and put it together with new gaskets (you can make your own with gasket paper and an exacto-knife). The MT isn't a race bike, or I'd tell you to pay $30+ for the kit at a Honda dealer.

I'm guessing the '74 had a magneto and points. Dress the points with a metal nail file if they're still pretty square to each other, then properly gap them. Otherwise replace them and the condensor and gap the new ones. Hook up a timing light and make sure the timing is advancing using the flywheel indicators. I never bother with a hand held tach, but if the 'dashboard' one works it will help. Use common sense. If it has CDI, the easiest check is to install one you know is good.

If you spend $30 for a book (Clymers, Haynes), or less on e-bay, it will tell you the same thing, and take you on from there.

Hope that helped.